Aside from the superb films he co-directs with his brother Jay, like “Baghead,” “Cyrus” and “Jeff Who Lives At Home,” we’ve been seeing more and more of Mark Duplass as an actor recently. The writer/director/star appears in cult comedy series “The League,” and has recently cropped up in indie festival favorites like “Your Sister’s Sister” and “Safety Not Guaranteed,” as well as in a role in Lawrence Kasdan‘s “Darling Companion.” But it looks like the actor’s just taken his first major studio role, in a film that’s one of our most anticipated of the year.

Despite Kathryn Bigelow‘s “Zero Dark Thirty” (her film about the hunt for 9/11 mastermind Osama Bin Laden) having been filming for quite some time now, it’s still adding cast members, and the latest on board, according to Deadline, is Duplass, who’ll take a ‘key supporting role.’ ‘Zero’ is very different from anything the actor’s done before, and he joins an absolutely first-class cast, including Jason Clarke, Chris Pratt, Joel Edgerton, Edgar Ramirez, Mark Strong, Jessica Chastain, Jennifer Ehle, Kyle Chandler, Harold Perrineau Jr., Nash Edgerton, Frank Grillo and Fares Fares. The film hits theaters on December 19th, 2012.

Elsewhere in casting news, Woody Allen‘s latest, which already has Bradley Cooper, Cate Blanchett and Alec Baldwin aboard, just got an extra dose of awesome with the addition of Bobby Cannavale to the cast. The actor’s perhaps best known for his TV turns on “Will & Grace” and the upcoming third season of “Boardwalk Empire,” along with his work with Thomas McCarthy on “The Station Agent” and “Win Win,” and it’s always a pleasure to see him on screen. As ever, there’s no word what role he’ll be playing, but the film will shoot in San Francisco later in the summer. [Deadline]

Finally, Ralph Fiennes is currently finishing up his sophomore directorial effort, “The Invisible Woman,” in which he plays Charles Dickens. But he’s already looking past that to the future, as Fiennes just signed on to Russia-set drama “The Two Women,” an adaptation of Ivan Turgenev’s tale. The film is directed by Vera Glagoleva (“One War“). [Deadline]